Electrode support



July 2, 1940. B. w. KINYON ELECTRODE SUPPORT Filed May 27, 1938INVENTOR.

ATTORNEY.

Patented July 2, 1940 UNITED STATES ELECTRODE SUPPORT Brice W. Kinyon,Bloomfield, N. J.,' assignor to Radio Corporation of America, acorporation of Delaware Application May 27, 1939, Serial No. 276,110

3 Claims.

t My invention relates to electrode assemblies for electron dischargedevices, particularly to means for supporting indirectly heated cathodesleeves in such assemblies.

6 The sleeve of an indirectly heated cathode is usually held at each endin insulating spacers, the cathode being supported in a central uprightposition inside other tubular electrodes attached to the spacers. Bossesor beads at the ends of it) the sleeves to prevent their endwisemovement increases the cost of the sleeve, complicates the assembly ofthe electrodes, and frequently binds the sleeves and causes bowing whenheated.

The object of my invention is improved support and locking means fortubular cathodes, such as cathodes for electron discharge devices, saidsupporting means and the cathode being inexpensive to make and assemblein said devices in such a way as to obviate bowing.

My invention is defined with particularity in the appended claims andthe preferred embodiment is described in the following specification andshown in the attached drawing in which Figure 1 shows an electrondischarge device with a cathode embodyingmy invention and Figures 2 and3 are detailed perspective and side views of specific cathode lockingmeans constructed according to my invention.

The tube shown in Figure 1 comprises an electrode assembly with sheetspacers l of insulating material, such as mica, engaging the ends of thecathode sleeve 2, which is exteriorly activated and contains aninsulated heating element, and also engaging the ends of the side rodsof anode 3 and grid 4. The assembly is mounted upon the stem of envelope5 which may be exhausted, sealed oh? and based in the usual manner.

The cathode 2 may be a sleeve of rolled and seamed sheet metal or adrawn seamless tube,

which is, according to my invention, straight sided and has no bosses orbeads characteristic of the usual cathode sleeve. The sleeve is lockedat one end in the spacer by a tab, ribbon or strip of metal 6 shown ingreater detail in Fig-.

ures 2 and 3, and its other end is preferably free to slide in itsspacer to permit longitudinal expansion of the sleeve without bowing orbuckling. The tab is bent at one end and formed as by die presses with asemi-circular loop I.

The tab is laid on the side of the sleeve with the tab extending beyondthe end of the sleeve and at a point 8 near the loop is attachedas bywelding to the side wall of the sleeve. In assembling, the end of thesleeve and the tab are threaded through the hole in the spacer to bringof the electrodes to accurately position the sleeve 10 l and positivelylock the sleeve in place before joining the electrode assembly to thepress leads. By pulling the outer end of the tab, to press the loopagainst the upper face of the spacer I, and

then swing or rotate the outer end of the tab 15 while under tension,toward the spacer, the tab may be kinked at the edge of the spacer hole.The set thus given the kinked tab positively locks the sleeve in thespacer against longitudinal movement in either direction. With the endof :0 the strip of metal at the loop butted against the side of thesleeve, the loop 7 presents a particularly firm shoulder and bearingsurface for the spacer. If the tab is made from. relatively heavy stock,the formed end of. the tab may of 25 course be shaped with a simpleright angle bend. Cathode sleeves round in cross section and about .025"in diameter are preferably secured in place with a metal tab of nickel.002" by .010 and about .40" long. 30

A strip of metal attached to one end of the cathode sleeve and bentupward on either side of its place of attachment with the bent-out por-ltions of the strip bearing against opposite sides of the spacereffectively locks the sleeve in place 5 and is inexpensive to assemblewith the sleeve. Cathode sleeves locked according to my invention arefree to expand longitudinally and will not bow or buckle when heated. Mynovel cathode tab eliminates the cost of embossing the 40 sleeve andcombines in a simple unitary structure an inexpensive cathode lock andconnector.

I claim:

1. An electron discharge device comprising a sheet spacer of insulatingmaterial, a tubular 45' cathode extending at one end through a hole insaid spacer, means for locking said cathode in said hole comprising astrip of metal attached to said one end of said cathode, the strip beingbent outwardly from the cathode at each side 50 of its point ofattachment and the bentout portions of the strip bearing againstopposite sides of the spacer. v

2. An electron discharge device comprising two spaced parallelinsulating spacers, a tubular u cathode supported at its ends in holesin said spacers, and means for locking said cathode against endwisemovement in said spacers comprising a strip of metal attached to one endof the cathode, the place of attachment being in the hole of one of thespacers and the strip being bent to overlie the edge of the hole in saidone spacer, the other end of the cathode being slidably guided by theother of said spacers.

3. A cathode assembly comprising a tubular metal sleeve exteriorly'activated, a connector and locking tab for said. sleeve comprising astrip of metal lying along the side of said sleeve parallel to the axisof the sleeve, said strip having a loop at one end, the strip adjacentthe loop being welded to said sleeve, the welded junction of the stripand the sleeve being near the end of the sleeve.

BRICE W. KINYON.

